1. Field of the Invention
The present invention relates to an apparatus for forming easy-open can ends and the tabs therefor. More specifically disclosed is a press assembly with a multiple lane conveyor operable in a main-frame press, and an appended but independent tab-forming apparatus, which conveyor, press and tab apparatus are operable by a single drive system.
2. Prior Art
Easy-open can end presses cooperating with tab-forming means are known in the art. U.S. Pat. No. 3,245,370--Bofinger discloses a device having a pair of counter-rotating turrets which slightly overlap at one portion of their peripheries. Each turret is provided with a plurality of spaced apertures that are coaxial or aligned with the apertures of the other turret in the region of overlap.
U.S. Pat. No. 3,683,665 relates to a press wherein main tooling is mounted to the main slide and auxiliary tooling, such as that which could be utilized for forming tabs, is driven by auxiliary slides driven off the same crankshaft as the main slide.
U.S. Pat. No. 3,366,086--Fraze teaches a method of forming container tops having tear strip tabs for removal and opening of the container tops. The basic steps of the method are illustrated in FIG. 1 and include a final stage of forming the finished top onto a container, generally a can.
A machine having a main dial plate rotating intermittently and carrying several can ends through work stations is disclosed in U.S. Pat. No. 3,470,837--Fraze et al. A feed mechanism has a stack of can ends, supported in a storage means for feeding through a feed spiral to the main dial plate for processing. The main dial plate is provided with relatively large apertures for nests to receive and support can ends of a particular size and shape. The tabs are preformed on a separate machine and are columnarly arranged above a rearward section of the slide.
U.S. Pat. No. 3,550,546--Eikenhorst illustrates a machine utilizing a main dial plate intermittently rotated to carry can ends through a series of work stations for conversion into easy-open can ends. Tabs for the easy-opening can ends are made in a tab die operable by the ram of the press of the machine, which tabs are fed on a strip to a staking station and affixed to the formed can ends. Tab and can end formation are performed as an integral operaton within the press by operation of the single ram. The tab die is generally located on the bolster bed in proximity to the dial plate and tab feeding mechanism.
U.S. Pat. No. 3,683,834--Potts et al discloses a press apparatus for applying ring tabs to a can end and for performing a plurality of sequential operations on a container end closure. The work stations are arcuately arranged on a rotating turntable 11 and various operations are performed on the can end closures as they pass through the work stations. Similarly, tabs are provided by a plurality of sequential operations in a progressive tab die section 13. Tabs and formed end closures are joined in the combination die assembly which includes progressive die section 13.
U.S. Pat. No. 4,026,226--Hahn et al shows a press apparatus and method for inverted conversion of easy-open metal container ends, which combines the functions of end and tab forming. The tab forming and end forming stations are disposed one above the other and are alternately operable by a vertically reciprocal slide assembly. Continuous stock strip is provided to a vertically arranged tab die set, which loops through and above the formed can ends. The can ends are provided in a dual lane transfer bed arrangement and the formed tabs are staked to the can ends.
A press for converting can ends and the like for an easy opening can structure is disclosed in U.S. Pat. No. 4,568,230--Brown. Upper and lower conversion tooling are located along a converting path at the top and bottom of a conveyor. The conveyor defines a dual lane plurality of stations on opposite sides of the center of the tooling for forming the shells moved by the conveyor. Tab forming tooling, auxiliary to the main tooling, is located on opposite sides of the conveyor and extends transversely of the main tooling. A tab forming path bridges the end of the converting path. Tabs are formed from a strip of metal fed through the tab tooling and guided in a loop to a staking and attachment station of the can end converting path for removal from the strip and attachment to the formed can ends. The can end tooling and tab forming tooling are cooperatively aligned between the guide rods and are operable by the same vertical reciprocal motion of the upper plate of the press.
U.S. Pat. No. 4,213,324--Kelly et al discloses a carrier means for a punch press to secure sheet metal work pieces through successive work stations while maintaining precision alignment between these work stations and relieving clamping pressure between the periphery of the sheet metal and the carrier means. The feed mechanism can be either a belt or a turret type assembly.
U.S. Pat. No. 4,456,873--Debenham et al illustrates an article retention system for transfer equipment particularly for carrying can ends through a series of progressive die work stations. A belt having openings therein for nesting a can end blank runs between fixed rail overlays on the can end edges to secure them in the belt during indexing. Spring actuated means are provided to maintain the belt in contact with the over-the-edge rails.
U.S. Pat. No. 4,475,278--Schockman et al discloses a specific mechanical press structure utilized in part in the press assembly of this application. Said patent is hereby incorporated by reference.
The prior art, generally, teaches a single press utilizing tooling arranged between a bolster and slide, which may have progressive tooling or die arrangements located thereon. Alternatively, the tabs of the easy-open can ends may be provided as finished pieces for joining with the formed can end blanks. Location and retention of the can ends within a conveying belt or turret has represented a problematic area.
In prior art presses where the tab tooling and main can end tooling are reciprocated by the same slide, the slide and its associated tooling area must be sufficiently large to accommodate the number of required tooling stations for both the tabs and can ends. Particularly in a multiple lane conversion press, this typically results in a press which has a high tonnage requirement. If the tab slide is separate from the main slide, it may be possible to make more efficient utilization of space. However, the tab slide is driven by a connecting arm connected to the same crankshaft as the main slide, there results a situation where the much smaller tab slide is being driven by a much larger drive system than is necessary because the crankshaft must also reciprocate the main slide. It is desirable to provide a conversion press assembly wherein the tab tooling and the main can end tooling can be conveniently arranged and the respective sets of tooling can be reciprocated by the efficient application of press tonnage.